Ekseni salınım eksenine paralel olarak salınım yapan dairesel kesitli borularda ısı transferinin deneysel olarak incelenmesi

Abstract

ÖZET Bu tez, ekseni salxnxm eksenine paralel olarak salxnxm ya pan silindirik borularda, acxsal salxnxmxn ve merkezcil yoğun luk kuvvetlerinin beraberce xsx transferine etkisinin deneysel calxsmasx sonuclarxnx sunar. Değişik salxnxm frekans lar xnda ya pılan akxş ve xsx transferi deneylerinde, periyodik olarak orta ya çxkan fiziksel etkilerin ortalamasx ölçüm sonuclarxnxn değer lendirilmesinde esas alxnmxstxr. Aynx Reynolds sayxsxnda, frekan- sxn artmasxyla deney elemanxndaki basxnc kaybxnda sxfxr frekans taki deney elemanxnxn verilerine göre değişiklik izlenmemiştir. Frekansxn xsx transferini iyileştirdiği gösterilmiştir. Bu nunla beraber sabit Reynolds sayxsxnda ve frekansta boru cidar sxcaklxgx ile akxskan sxcaklxgx arasxndaki fark artxrxldxgxnda merkezcil yoğunluk etkileri önemli olmaktadxr. Bunun neticesinde acxsal salxnxmxn xsx transferine etkilerinin azalabileceği de gösterilmiştir. viii

SUMMARY This thesis reports the results of an experimental study of combined influence of angular oscilating effects and centripetal buoyancy on the heat transfer in a cylindrical tube which, oscilates about an axis parallel to its axis of symmetry. Owing to the periodical occurrence of physical effects in fluid flow and heat transfer experiments at a different oscilating frequency, the mean values of measurements were taken for data processing. At the same Reynolds number, no varitions in overal pressure drop accross the test section was observed with the increasing frequency, by comparing derived data for test section at zero frequency. It is demonstrated that, frequency tends to improve heat transfer. However, as the motivating temperature difference for heat transfer between the pipe wall and fluid increases, at the fixed Reynolds number and frequency, it is apperant centripetal buoyancy becames significant. Consequently the angular oscilating effect on heat transfer may be nullifed and this is also demonstrated. IX